Maybe this is kind of a dumb question ....I bought my Evo X GSR new in 2010 and took the stock Yokohamas off pretty much the day I drove the car home. They've been sitting in my garage ever since (yes I'm lazy) and I've been running Continental DWSs ever since. Just wondering can I still use the Yokohamas? Do tires go "bad" if they are never used?

 

They should still be fine if they are not exposed to Ozone gas or Ultra-Violet lights.

 

Yes, they can dry rot....mount them and see if they start to crack, if so no good. 6 years is a long time to have tires sit anyway..

 

By Ozone, do you mean stored outdoors? They've been in my garage in NJ .. so some exposure to cold but they've been indoors the whole time.

 

UV and O3 could be produced (cause) by a number of different machines as well as naturally occurring events. I would not worry about it too much if you are not near an industrial site. Do what the poster above said and mount/pressurize them. You'll see if they are dry-rotted (symptom)or not.

 

Our experience has been that when properly stored and cared for, most street tires have a useful life in service of between six to ten years.